Update to Laravel 4.2

@adrianmacneil this updates the `illuminate/database` dependency to `~4.2.0`. Trying to keep up with Laravel versions upstream. Since Laravel 4.2 bumped requirements to PHP 5.4, I added that requirement here. Tag `1.0.0` would still be usable when you need Laravel 4.1 and/or PHP 5.3 support.

Any objections to me merging this?